Lead sharpener

ABSTRACT

A lead sharpener with oppositely secured, cup-shaped upper and a lower parts which are rotatable relative to each other for grinding a lead retained in a lead holder. A holding member for receiving the lead holder is supported by the upper part, which holding member is pivotably mounted on the upper part relative to an axis which is parallel to the axis of rotation and further for movement to vary the angle of inclination relative to the axis of rotation, so that a desired angle may be ground on a lead retained in the lead holder.

United States Patent c110 1451 Oct. 17, 1972 [54-] LEAD SHARPENER 510,518 12/1893 Price "144/2811 [72] inventor: Antonio Ch, Feldbumenweg 47, 1,202,325 10/1916 Simmons ..l44/28.l

Zurich Switzerland 3,042,003 7/1962 Cayo ..l44/28.l

v 22 Filed: Oct. 12 1970 FOREIGN PATENTS OR APPLlCATlONS 273 979 6/1951 Switzerland; ..l44/28.72 N 9, 8 [21] 0 7 88 415,855 1947 Italy ..l44/28.l [30] Foreign Application Priority Data Primary Examiner-Theron E. Condon June 18, 1969 Switzerland 9543/69 Attorney-nynn and Fnshauf June 18, 1970 Germany 20 29 929.0 [57] ABSTRACT [52] US. Cl ..144/28.11 A lead Sharpener with oppositely secured, cup shaped [51] Int. Cl. ..'...B43l 23/00 pp d a lower parts which are rotatable relative to [58] Field of Search "145/311, 3.32, 3.9; 144/28.1, each other for grinding a lead retained in a lead 144/231 1, 233 284, 2&6, 2811, 2&8, holder. A holding member for receiving the lead 239 holder is supported by the upper part, which holding member is pivotably mounted on the upper part rela- [56] References Cited tive to an axis which is parallel to the axis of rotation and further for movement to vary the angle of inclina- UNITED STATES PATENTS tion relative to the axis of rotation, so that a desired 1 b l d 1 2,242,458 5/1941 Dessonnaz ..144/2s.1 ig z f e gmmd a ea tamed m the ead 479,303 7/1892 Price ..l44/28.l1 7 429,689 6/1890 Jones ..144/28.1 12 Claims, 7 Drawing Figures 20 T 56 as 54 3% 24 27 I 5 n I n) 6 I 56 II I I W sion of an improved sharpening apparatus which is relatively simple and sturdy in construction, economical to manufacture, and otherwise adapted to meet the requirements for a successful commercial use.

Subject matter of the present invention: to provide a marking lead sharpener, comprising an upper part, a lower part, said upper and lower parts being relatively rotatable on a common axis of rotation, the inner surface of the lower part being adapted to carry a grinding surface, a holder for receiving a lead holder, said holder being pivotably mounted on the upper part for pivotal movement relative to an axis which is parallel to the axis of rotation of the upper and lower parts and for pivotal movement to vary the angle of inclination of the axis of the holder relative to the axis of rotation so that a desired angle may be ground on a lead retained in the lead holder.

It is still a further object of this invention to provide grinding surface means which are interchangeable and which are detachably fixed to the lower part of the ap paratus.

The invention itself may be best understood by reference to the following description as when taken in accordance with the following and accompanying drawing, wherein:

FIG. 1 is a vertical section through a lead sharpener according to the present invention and is a section taken on the line II of FIG. 2;

FIG. 2 is a plan view of the lead sharpener;

FIG. 3 is a view of a part of the lead sharpener of FIG. 2 viewed in the direction of arrow B;

FIG. 4 is a section taken on the line IVIV of FIG. 2; FIG. 5 is a view of a part of the lead sharpener of FIG. 2 from underneath;

FIG. 6 is a longitudinal section through a holder for use with the lead sharpener of FIG. 1, intended for grinding compass leads; and

FIG. 7 is a plan view of the holder of FIG. 6.

Referring to the drawings, there is shown a lead sharpener or sharpening apparatus comprising an upper cylindrical part 1 and a lower cylindrical part 2 which is rotatable about a vertical axis. A horizontal plane 4 defines the interface between the upper and lower parts. The lower part 2 is substantially hollow and has a frusto-conical inner wall 2a which tapers in the downward direction away from the upper part. Grinding means in the form of, for example, a strip of abrasive paper 3 or other emery materials are positioned on or against the frusto-conical inner wall 2a. When flattened out the strip of abrasive paper 3 has the shape of a sector of a ring, so that it accurately fits against the frusto-conical inner wall with its ends abutting. As an alternative, instead of using a strip of abrasive paper, it is possible to apply abrasive particles directly to the frusto-conical inner wall 2a, but the use of strips of abrasive paper 3 has the advantage that these strips can be easily replaced when the abrasive is exhausted. The

. strip of, abrasive paper 3 is clamped in position by a holder 9 which itself is retained in position by an upwardly directed screw 18. One side of the holder 9 abuts against a central projecting base member 16, and, on tightening the screw 18, the holder 9 is pressed against the frusto-conical wall 2a so securing the strip of abrasive paper 3 in position. When the screw 18 is unscrewed a spring 17 raises the holder 9 away from the bottom of the lower part 2, so that the strip of abrasive paper 3 can be easily removed and a new one inserted.

A holding means for lead carriers or lead holders 33, shown as a holder 5 is located on the upper part 1 and is mounted in such a way as to be piv-otable relative to the upper part 1. The holder 5 has two recesses 10, 11 for receiving the lead holders 33 carrying leads 35 to be sharpened or ground. The axis of the pivotal movement of the holder 5 extends parallel or approximately parallel to the axis of rotation of the upper part 1. Also the longitudinal axis of the recesses 10 and 11 are extending parallel or approximately parallel to the axis of pivotal movement of the holder 5. The holder 5 is connected to the upper part 1 by means of a slider 19 which can be radially displaced in a groove 21 in the upper part 1 in the direction of the double arrow A (FIG. 4). The slider 19, and hence the holder 5, may be retained and fixed in a desired position by means of a screw 20. The slider 19 has an oblong hole 37 therein, and through this hole passes a threaded portion 36 of the screw 20. The holder 5 is articulated to the upper part 1 by means of upper and lower ball-and-socket joints each of which has a spherical portion 7 engaging in a ball cup or socket portion 6. The lower spherical portion 7 is rigidly connected to or is integral with the upper part 1. The upper spherical portion 7 is located on the slider 19 and projects downwardly therefrom. In this way a change in the inclination of the longitudinal or swivel axisof the holder 5 may be achieved by displacing the slider 19 in the direction of the double arrow A. A change in the inclination of the swivel axis of the holder produces a change in the angle which may be ground on the marking lead 35. Accordingly, when the slider 19 is moved inwardly a more obtuse angle may be ground on the lead 35. Conversely, if the slider 19 is moved outwardly, a more acute angle may be ground. The holder 5 can, in addition, be pivoted about the two spherical portions 7, as is indicated by the double arrow C in FIG. 2. This movement is of easy action. In this way a lead 35 carried .by a lead holder 33 in the recess 10 of the holder 5 can easily be pressed against the strip of abrasive paper 3 by hand to an extent merely governed by feel while rotating the upper part 1 by hand relative to the lower part 2, to cause the lead 35 to be ground. Thus, in summary, the holder 5 can be pivoted to a limited extent about an axis substantially parallel to the axis of rotation of the upper part 1, and, in addition, can have the inclination of its swivel axis varied to a limited extent.

In order to accommodate a normal commercial hexagonal cross-section lead holder 3.3, in which the lead 35 to be sharpened is held in position by means of a chuck 34 also known as clutch pencils the recess 10 is circular in cross-section and has an axis which extends approximately parallel to the axis of rotation of the upper part 1. The diameter of the recess 10 is slightly larger than the maximum width of the hexagonal cross-section lead holder 33. This ensures that the lead holder 33 can be rotated easily by hand about its own axis while it is disposed in the recess 10 and yet the lead holder is still efficiently guided.

Moreover, the holder contains a second recess 11 for a lead holder 33. At the upper end of the recess 11 there are two chuck-like clamping members 23, 24. The clamping members 23, 24 have engagement means 25 or teeth for engaging each other so that they may move together towards or away from one another. The clamping member 23 is pivotably mounted about a screw 39 or pin mounted on the holder 5, while the clamping member 24 is pivotally mounted about a second screw 38 or pin which is spaced apart from the screw 39. One end of a leaf spring 26 abuts the clamping member 24, while the other end of the spring 26 is rigidly secured to the lower end of the holder 5 by a screw 40 shown in FIG. 3. The spring 26 biasses the clamping members 23, 24 towards one another. The mutually facing inner surfaces of the clamping members 23, 24 are provided with obtuse-angled recesses, so that, between them they define a hexagonal recess substantially of the cross-sectional shape of normal hexagonal cross-section lead holders 33. By the provision of the clamping members 23, 24, it is possible to accommodate lead holders of different sizes in the recess 11. In addition, the lead holder 33 occupies an accurately defined fixed position relative to the holder 5 and this position is maintained during the grinding process of the lead 35. This is in contrast to the recess in which relative rotation between the lead holder 33 and the recess is provided for.

The upwardly extending base member 16 carries a frusto-conical brush l4 rigidly secured thereto, the brush 14 tapering in an upward direction. The brush 14 serves to clean grinding dust off ground leads after the grinding process. Above the brush 14, two openings 27, 28 of different diameter are provided. In the openings 27, 28 lead holders 33 can be inserted for cleaning the ground lead carried thereby. The radial spacing of the openings 27, 28 from the axis of rotation of the upper part 1 is less than the radial spacing of the recesses 10, 11 in the holder 5. The brush 14 may be made preferably from plush, because this material possesses relatively soft hairs. In order to clean grinding dust from ground leads the lead holder 33 is inserted into either opening 27 or opening 28 and then the upper part 1 is rotated relative to the lower part 2 by means of the lead holder 33 which is held by hand.

The center of the upper part 1 contains a vertical bolt or pin which is rigidly secured thereto and which extends through the lower part 2. In the lower part 2 this pi is rotatably guided so that the upper part 1 can be easily rotated relative to the lower part. 2. In order to enable the upper part 1 to be easily detached from the lower part 2, for example, for cleaning or for replacing the strip of abrasive paper 3, detachable coupling means are provided. As shown in FIG. 5, the detachable coupling comprises a wire spring 31 which is engaged in a peripheral groove 32 at the lower end of the pin 15. The spring 31 is located in a recess 30 in the bottom of the lower part 2 and is fixed in position by means of a screw 8. When a predetermined upward force is exerted between the upper part 1 and the lower,

part 2 the spring 31 is distorted and disengages the groove 32 to allow the upper part 1 and the lower part 2 to be separated from one another. Conversely, the spring 31 jumps into the groove 32 automatically when the spring 31 and the groove are forced into alignment.

In order to reduce the weight of the upper part 1, small cut-out portions 56 or grooves are provided in the upper part 1.

During grinding of a lead care must be taken to remember that for an obtusely ground lead the lead need only be relatively short, while to grind for more acute angles longer leads are required. To enableadjustment of the lead to the desired length prior to grinding, an extension 41 or stop member is provided on a part of the circumference of the upper part 1 whose upper edge is inclined to the horizontal plane of the top of the upper part 1. The procedure for adjusting the length of the lead consists in setting the underside of the chuck 34 of the lead holder 33 on the edge 54 or rim of the upper part 1 and the lead 35 to be ground is chosen to have a length such that it abuts the extension 41 below. Preferably, a scale is provided on the edge 54 to enable the length of the lead to be conveniently adjusted commensurate with a desired angle to be ground.

In order to enable the lead sharpener to be used for sharpening leads of compasses, an accessory holder 43 is provided. The accessory holder 43 is shown in FIGS. 6 and 7. An insert 44 which'is a part of a compass comprising a chuck 34 and a lead 35 is removed from the compass. The insert 44 is then inserted in a sleeve 43 of hexagonal cross-section and clamped in position by means of a wedge-like securing element 45 having an inclined surface 48. The inclined surface 48 presses against the surface of the cylindrical portion of the insert 44 and retains the same in position. In order to prevent the insert 44 from rotating relatively to the sleeve 43, a transverse pin 46 is provided in the sleeve 43 and the pin 46 engages a fork 50 at the upper end of the insert 44, so that the inset 44 is always positioned at the same position in the sleeve 43. The sleeve 43 provided with the insert 44 secured therein is inserted in the recess 11, and held in position by the clamping members 23, 24 to prevent it from rotating relative to the upper part 1.

Since the construction of the compass insert 44 varies depending upon their manufacturer, the securing element 45 is provided with a second inclined surface 49 having a different inclination from the inclined surface 48. As a result, different constructions of inserts 44 can also be clamped in position in the sleeve 43. It is also possible to provide a plurality of securing elements 45 having various different inclined surface in order to retain in position in the sleeve 43 inserts 44 of various constructions.

Grinding of the leads is carried out by inserting a lead holder 33 with a lead 35 to be ground in the recess 10 of the holder 5. The lead holder 33 is held by hand and the upper part 1 is rotated relative to the lower part 2 by executing a circular motion with the hand together with the upper part 1. The upper part 1, therefore, rotates relative to the lower part 2 about the pin 15. The lead 35 moves along the strip of abrasive paper 3, but does not rotate on its own axis. Since the holder 5 can be pivoted in the direction of the double arrow C,

the all-round grinding of the lead 35 may be achieved by light pressure against the strip of abrasive paper 3. The result is a slender tapered lead terminating in a point. According to the inclination of the swivel axis of the holder 5, which is determined by the radial displacement of the slider 19 in the direction of the double arrow A, the angle of the ground lead may be varied at will.

When, by contrast, the lead holder is inserted in the recess 11, then the lead holder 33 is unable to rotate in this recess relative to the upper part 1 because it is clamped between the clamping members 24, 25 and an inclined substantially plans surface is ground on the marking lead. The angle of the inclined plane surface is again determined by the inclination of the axis of the holder 5. If now, after grinding of such an inclined surface, the lead holder is turned through 180 and a further inclined plane surface is ground on the lead, then the lead assumes the shape of a wedge. In contrast to the first-described example for forming a tapered lead terminating in a point, the upper part 1 is now usually not rotated through a full-circle relative to the lower part 2, but the upper part 1 is rotated relative to the lower part merely through a limited angle, for ex ample, of 90. An analogous procedure is adopted with the sleeve 43, i.e. instead of a lead holder 33 the sleeve 43 is inserted into the recess 11.

It is possible for more than one holder 5 to be provided on the upper part 1; for instance, a second holder pivotable in the same manner as the holder 5 shown may be provided diametrically opposite to the holder 5.

It will be understood that the present invention is not limited to the specific materials, steps and other specific details described above and may be carried out with various modifications without departing from the scope of the invention as defined in the appended claims. Accordingly, a

What is claimed is:

1. Lead sharpener, comprising an upper part (1) and a hollow part (2),

said upper part being rotatable relative to said lower part on an axis of rotation said lower part (2) having an inner surface adapted to carry grinding means (3);

holding means (5) formed with at least one recess (10, 11) for receiving lead holders, said holding means being pivotably mounted on said upper part for pivotal movement about a pair of mutually perpendicular directions, one direction being substantially parallel to said axis of rotation (15) and said holding means (5) being located spaced from said axis of rotation (15) of said upper part; and

means (19, for adjusting the angle of inclination of said one direction relative to said axis for varying the angle ground on a lead retained in said holding means. 2. Sharpener as defined in claim 1, wherein said holding means is formed with two lead receiving recesses, (10, ll), (5),

axis of pivoting of said holding means being arranged between said two recesses, said axis of rotation, said axis of pivoting and the longitudinal axis of said recesses being substantially parallel.

3. Sharpener as defined in claim 1, wherein said adjusting means includes slider means connected to said relative to said upper part.

4. Sharpener as defined in claim 3, wherein said slider means engages in a groove in said upper part and is retainable in position relative to said upper part by screw means passing through an oblong hole in said slider means.

5. Sharpener as defined in claim 1, comprising ball and socket joint means (6, 7) pivotably mounting the holding means (5) on said upper part (1 6. Sharpener as defined in claim 1, wherein said inner surface of the lower part is; frusto-conical and tapers in a direction away from said upper part, said frusto-conical surface supporting an interchangeable strip comprising grinding material, means for detachably fixing said strip to said inner surface, said fixing means being disposed adjacent the bottom of said lower part.

7. Sharpener as defined in claim 6 wherein the fixing means comprises a wedge (9) located against the bottom surface of the lower part (2) and bearing against the frusto-conical surface, and means (18) accessible from beneath the bottom surface of the lower part securing the wedge in position to clamp the strip (3) by wedging action against the frusto-conical surface upon tightening of the wedge against the bottom surface of the lower part.

8. Sharpener as defined in claim 1, wherein a frustoconical brush is fixed in said lower part for cleaning the lead after processing, and at least one opening in said upper part for retaining a lead holder with its lead in engagement with said brush.

9. Sharpener as defined in claim 1, wherein said upper part has a top edge and is provided at the outer circumferential surface thereof with an elongated index member inclined with respect to the top edge of the upper part for adjusting the length of the lead to be ground.

10. Sharpener as defined in claim 1, for use with a polygonal lead holder wherein said holding means comprise two co-acting clamping members (23, 24), having oppositely directed clamping surfaces adapted to engage the straight sides of the polygonal lead holder, said clamping members being movable between an inoperative position in which a lead holder may be inserted into said recess, and an operative position in which a lead holder is retained therebetween, and resilient means (26) for biassing said clamping members to the operative position.

11 Sharpener as defined in claim 1, comprising a central pin (15) rigidly connected to the top one of said parts (1) and passing through the other of said parts, the pin being rotatably mounted in said other part, said pin defining the axis of rotation; a coupling spring (31) co-acting with said pin secured to the bottom of the other part, said spring being engageable with a groove (32) in said pin (15) to detachably secure said upper and lower parts together.

12. Sharpener as defined in claim 1, in combination with a sleeve (43) for a compass including a lead to be ground, and means for securing said part in said sleeve, said securing means comprising a wedge member (45) having at least one inclined surface (48, 39) for clamping said part in said sleeve, said sleeve being of a diametrical size to fit into at least one of said recesses (10, 11) to form a lead holder. 

1. Lead sharpener, comprising an upper part (1) and a hollow part (2), said upper part being rotatable relative to said lower part on an axis of rotation (15), said lower part (2) having an inner surface adapted to carry grinding means (3); holding means (5) formed with at least one recess (10, 11) for receiving lead holders, said holding means being pivotably mounted on said upper part for pivotal movement about a pair of mutually perpendicular directions, one direction being substantially parallel to said axis of rotation (15) and said holding means (5) being located spaced from said axis of rotation (15) of said upper part; and means (19, 20) for adjusting the angle of inclination of said one direction relative to said axis for varying the angle ground on a lead retained in said holding means.
 2. Sharpener as defined in claim 1, wherein said holding means is formed with two lead receiving recesses, (10, 11), (5), the axis of pivoting of said holding means being arranged between said two recesses, said axis of rotation, said axis of pivoting and the longitudinal axis of said recesses being substantially parallel.
 3. Sharpener as defined in claim 1, wherein said adjusting means includes slider means connected to said holding means (5) and radially displaceably mounted relative to said upper part.
 4. Sharpener as defined in claim 3, wherein said slider means engages in a groove in said upper part and is retainable in position relative to said upper part by screw means passing through an oblong hole in said slider means.
 5. Sharpener as defined in claim 1, comprising ball and socket joint means (6, 7) pivotably mounting the holding means (5) on said upper part (1).
 6. Sharpener as defined in claim 1, wherein said inner surface of the lower part is frusto-conical and tapers in a direction away from said upper part, said frusto-conical surface supporting an interchangeable strip comprising grinding material, means for detachably fixing said strip to said inner surface, said fixing means being disposed adjacent the bottom of said lower part.
 7. Sharpener as defined in claim 6 wherein the fixing means comprises a wedge (9) located against the bottom surface of the lower part (2) and bearing against the frusto-conical surface, and means (18) accessible from beneath the bottom surface of the lower part securing the wedge in position to clamp the strip (3) by wedging action against the frusto-conical surface upon tightening of the wedge against the bottom surface of the lower part.
 8. Sharpener as defined in claim 1, wherein a frusto-conical brush is fixed in said lower part for cleaning the lead after processing, and at least one opening in said upper part for retaining a lead holder with its lead in engagement with said brush.
 9. Sharpener as defined in claim 1, wherein said upper part has a top edge and is provided at the outer circumferential surface thereof with an elongated index member inclined with respect to the top edge of the upper part for adjusting the length of the lead to be ground.
 10. Sharpener as defined in claim 1, for use with a polygonal lead holder wherein said holding means comprise two co-acting clamping members (23, 24), having oppositely directed clamping surfaces adapted to engage the straight sides of the polygonal lead holder, said clamping members being movable between an inoperative position in which a lead holder may be inserted into said recess, and an operative position in which a lead holder is retained therebetween, and resilient means (26) for biassing said clamping members to the operative position.
 11. Sharpener as defined in claim 1, comprising a central pin (15) rigidly connected to the top one of said parts (1) and passing through the other of said parts, the pin being rotatably mounted in said other part, said pin defining the axis of rotation; a coupling spring (31) co-acting with said pin secured to the bottom of the other part, said spring being engageable with a groove (32) in said pin (15) to detachably secure said upper and lower parts together.
 12. Sharpener as defined in claim 1, in combination with a sleeve (43) for a compass including a lead to be ground, and means for securing said part in said sleeve, said securing means comprising a wedge member (45) having at least one inclined surface (48, 39) for clamping said part in said sleeve, said sleeve being of a diametrical size to fit into at least one of said recesses (10, 11) to form a lead holder. 